The former Everton man limped out of the Canaries' 2-1 win over Sunderland on Monday, having only been on the field ten minutes as a substitute. Vaughan has had plastic surgery on a lip injury already this term and missed the beginning of the season with a knee complaint, but club boss Paul Lambert confirming the latest setback is a fresh concern. "He just came back from a knee injury, the only thing is it's not the same one as he hurt before, we'll have to wait and see," Lambert told BBC Radio Norfolk. "His knee is locked which is not a good sign, we'll know more on Tuesday. He's really unlucky and is a bit down as you can imagine." Vaughan, 23, had knee surgery on two occasions in his Everton days while a severed artery and dislocated shoulder rank high among the worst setbacks of the striker's injury-hit career.